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small-head snakeweed, sticky snakeweed, threadleaf snakeweed

Habit Subshrubs, 20–140 cm.
Stems

glabrous or minutely hispidulous.

Leaves

basal and proximal absent at flowering;

cauline blades 1-nerved, linear or filiform to narrowly oblanceolate or lanceolate, 0.5–2.2(–4) mm wide, little reduced distally.

Involucres

cylindric, 1–1.5 mm diam.

Ray florets

1(–2; each enclosed by conduplicate inner phyllary);

corollas yellow, (1.5–)2–3.5 mm.

Disc florets

1, sometimes 2 (functionally staminate; corollas broadly obdeltate-funnelform, throats widely flaring, lobes 1/3 corolla lengths, recurved-coiling).

Heads

(2–6, sessile to subsessile, in compact glomerules) in flat-topped arrays.

Cypselae

1–1.8(–2.5) mm, faces densely strigoso-sericeous;

pappi (rays, readily falling) of 1 series of narrowly lanceolate-oblong scales.

Phyllary

apices flat.

2n

= 8, 16, 24, 32.

Gutierrezia microcephala

Phenology Flowering (Jun–)Jul–Dec(–Feb).
Habitat Grasslands, chaparral, oak or oak-pine woodlands, usually over gravelly or rocky limestone or gypsum substrates, dunes
Elevation 800–2500 m (2600–8200 ft)
Distribution
from FNA
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Veracruz, Zacatecas)
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Discussion

Gutierrezia microcephala is recognized by its perennial habit and its small, tightly clustered heads, each with 4–8 phyllaries and 1(–2) ray and disc florets. Each ray floret is enclosed by a conduplicate inner phyllary. Forms of G. sarothrae with few florets in each head can be distinguished by their bisexual and fertile disc florets and tubular-funnelform disc corollas.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 20, p. 92.
Parent taxa Asteraceae > tribe Astereae > Gutierrezia
Sibling taxa
G. arizonica, G. californica, G. petradoria, G. pomariensis, G. sarothrae, G. serotina, G. sphaerocephala, G. texana, G. wrightii
Synonyms Brachyris microcephala, G. sarothrae var. microcephala, Xanthocephalum microcephalum
Name authority (de Candolle) A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 74. (1849)
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